This invention relates to the detection and location of electrical defects in electric power and distribution lines, gas-filled telephone cables and associated components and equipment, and more particularly to a combination ultrasonic and VHF detector for locating such defects.
It is desirable, for example, for power company line crews and others to be able to locate defects in power lines and associated equipment and to confirm the effectiveness of maintenance or repair work done to correct the defects. Such defects as loose insulators or hardware, as well as other deficiencies associated with energized power lines, result in arcing or sparking, including corona discharge, which are not only damaging to electrical equipment but also produce ultrasonic and very high frequency emissions.The latter are sources of undesirable radio and television interference.
Ultrasonic and VHF probes have been utilized heretofore for the purpose of detecting and locating such defects as mentioned above. However, they have been provided only as separate units for use individually as alternative devices to perform the same function. Accordingly, the results have been less than completely satisfactory since each type of probe has certain inherent limitations. For example, VHF probes without expensive directional antennas are substantially non-directional and therefore require excessive operational time for pinpointing the source of a defect. On the other hand, ultrasonic probes are quite directional and therefore it is a frequent occurrence that weak ultrasonic defect sources, such as small leaks in gas-filled overhead telephone cables, or small power line sparks, are passed over.